Certain turbine engine manufacturers assemble large cylindrical roller bearings on bearing shafts. Either the bearing race or the shaft may be heated during assembly. If the cylindrical rolling elements, referred to as rollers herein, of the bearing are not supported within their cages with the parts perfectly mated, then scoring damage to the rollers and/or the shaft may occur during the assembly process. Such damage may lead to early engine failure. After the engine is assembled, it is charged with turbine engine oil and run at an elevated temperature during a test called a green run. After the green run, the engine oil is drained and the turbine engine is recharged with turbine engine oil in preparation for normal service. During the green run and normal service, the engine oil is circulated through a filter. It is necessary that the engine filter not be clogged by materials in the engine oil, which might lead to lubricant starvation.
To solve the scoring problem, some manufacturers use a petrolatum or petrolatum-like products as an assembly aid on the rollers. However, the relatively low melting point of these products limits their ability to hold parts, i.e., as an assembly aid, during assembly at elevated temperatures. Under normal operating conditions, such assembly aids typically take less than one minute to fail, i.e. to melt sufficiently so that they release from the parts using the drop test described herein. Moreover, petrolatums are insoluble in polar fluids, such as esters.
Petrolatum or petrolatum-like products are currently used because they melt at the engine operating temperature and can be drained, while molten, along with the turbine engine oil. However, it would be preferable to have an assembly aid that is soluble in engine lubricants and which also has holding strength at the elevated temperatures at which certain engine manufacturers, such as aviation turbine engine manufacturers, assemble the engines.
Other uses for compositions having such characteristics also exist. For example, remaining solid at elevated temperatures, yet possessing the tackiness or stickiness needed in an assembly aid, is also useful in hot melt adhesives used in a variety of applications.